无证约束？发布到主题 *from* pubsub 触发器

Question

我不知道我是不是疯了，或者这是一个没有记录的限制（我已经搜索了 GCP API 文档）：

是否可以在“主题 A”上有一个带有 pubsub 触发器的云函数，并在该云函数中向“主题 B”发布一条消息。

我已经尝试了所有其他运行相同代码的触发器（云函数作为 HTTP 触发器、云存储触发器、Firebase 触发器），它们都成功发布到主题。 但是，当我（几乎是字面意思）将我的代码复制粘贴到 pubsub 触发器中时，在使用消息之后，当它尝试将它自己的消息发布到下一个主题时，它只是挂起。尝试发布时，该函数只是超时。

所以回顾一下，在 GCP 中是否可以执行以下操作？

PubSub Topic A --> Cloud Function --> Pubsub Topic B

提前感谢您的澄清！这一切都在 Java 11 中。这是代码：

...<bunch of imports>

public class SignedURLGenerator implements BackgroundFunction<PubSubMessage> {
  private static final String PROJECT_ID = System.getenv("GOOGLE_CLOUD_PROJECT");
  private static final Logger logger = Logger.getLogger(SignedURLGenerator.class.getName());

  /**
  * Handle the incoming PubsubMessage
  **/
 @Override
  public void accept(PubSubMessage message, Context context) throws IOException, InterruptedException {
    String data = new String(Base64.getDecoder().decode(message.data));
    System.out.println("The input message is: " + data.toString());

    //Do a bunch of other stuff not relevant to the issue at hand...

    publishSignedURL(url.toString());
  }

  //Here's the interesting part
  public static void publishSignedURL(String message) throws IOException, InterruptedException {
    String topicName = "url-ready-notifier";
    String responseMessage;
    Publisher publisher = null;
    

    try {
      // Create the PubsubMessage object
      ByteString byteStr = ByteString.copyFrom(message, StandardCharsets.UTF_8);
      PubsubMessage pubsubApiMessage = PubsubMessage.newBuilder().setData(byteStr).build();
      System.out.println("Message Constructed:" + message); 
      //This part works fine, the message gets constructed

      publisher = Publisher.newBuilder(ProjectTopicName.of(PROJECT_ID, topicName)).build();
      System.out.println("Publisher Created.");
      //This part also works fine, the publisher gets created

      publisher.publish(pubsubApiMessage).get();
      responseMessage = "Message published.";
      //The code NEVER GETS HERE.  The message is never published.  And eventually the cloud function time's out :(    

    } catch (InterruptedException | ExecutionException e) {
        System.out.println("Something went wrong with publishing: " + e.getMessage());
      }

    System.out.println("Everything wrapped up.");

  }

编辑 根据要求，这是我当前的 POM

    <?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
      <modelVersion>4.0.0</modelVersion>
      <groupId>cloudfunctions</groupId>
      <artifactId>pubsub-function</artifactId>
      <version>1.0-SNAPSHOT</version>
    
      <properties>
        <maven.compiler.target>11</maven.compiler.target>
        <maven.compiler.source>11</maven.compiler.source>
      </properties>
    
      <dependencies>
        <dependency>
          <groupId>com.google.cloud</groupId>
          <artifactId>libraries-bom</artifactId>
          <version>20.6.0</version>
          <type>pom</type>
          <scope>import</scope>
      </dependency>
        <dependency>
          <groupId>com.google.cloud.functions</groupId>
          <artifactId>functions-framework-api</artifactId>
          <version>1.0.1</version>
          <type>jar</type>
        </dependency>
        <dependency>
          <groupId>com.google.cloud</groupId>
          <artifactId>google-cloud-storage</artifactId>
          <version>1.117.1</version>
        </dependency>
        <dependency>
         <groupId>com.google.cloud</groupId>
          <artifactId>google-cloud-pubsub</artifactId>
          <version>1.113.4</version>
        </dependency>
        <dependency>
          <groupId>com.google.api</groupId>
          <artifactId>gax</artifactId>
          <version>1.66.0</version>
        </dependency>
        <dependency>
          <groupId>com.google.api</groupId>
          <artifactId>gax-grpc</artifactId>
          <version>1.66.0</version>
        </dependency>
        <dependency>
          <groupId>org.threeten</groupId>
          <artifactId>threetenbp</artifactId>
          <version>0.7.2</version>
        </dependency>    
      </dependencies>
    </project>

Answer 1

您可以尝试在发布者客户端中显式设置流控制参数吗？像这样

       publisher = Publisher.newBuilder(ProjectTopicName.of(PROJECT_ID, topicName)).setBatchingSettings(BatchingSettings.newBuilder()
                .setDelayThreshold(Duration.of(10, ChronoUnit.SECONDS))
                .setElementCountThreshold(1L)
                .setIsEnabled(true)
                .build()).build();

我不知道会发生什么，可能是 PubSub 的默认和全局配置。如果不是这样，我会删除这个答案。

---

编辑 1

这里是 Publisher 父类上的构建器类的屏幕截图

您拥有该库的所有默认值。但是，您观察到的行为是不正常的。即使您在 PubSub 触发器中，默认值也必须保持默认值。我将打开一个问题并直接将其转发给团队。